This invention relates to aircraft deicers and more particularly to an improved inflatable deicer or boot adapted for attachment to the airfoil of an aircraft for use in retarding the accumulation of ice or to remove or break up ice accumulation.
Aircraft inflatable deicers, pads or boots are made of resilient material such as rubber and attached to the leading edge of an airfoil and extend rearwardly therefrom. The deicer has a series of inflatable passages or tubes which are distended by inflation pressure to break up ice accumulation which tends to form on the surface of the deicer. The passages or tubes are deflated by releasing the pressure medium and drawing a vacuum thereon. The normal sequence of operation is a continuous cycling of the inflation and deflation process. The present invention is an improvement on the structure and operation of prior deicers wherein the invention recognizes the need to differentiate between the stagnation line and the leading edge of an airfoil. The stagnation line of the wing of an aircraft is the line along which the air separates above and below such line on the wing whereas the leading edge of the wing is the foreward most edge of the wing. In the case of a symmetrical wing, the leading edge and the stagnation line are the same; however, in the case of a non-symmetrical or asymmetrical wing, the stagnation line is either below or above the leading edge of the wing. The present invention locates the deicer's inflatable tubes above and below the stagnation line while leaving the area immediately adjacent the stagnation line free of inflatable tubes. The advantage of this construction is a clamshell effect which takes place on the ice when the inflatable tubes on each side of the stagnation line inflate causing the ice to break in the non-inflatable area around the stagnation line. The wind stream over the airfoil then removes the ice build-up from the airfoil's leading edge. On some asymmetrical airfoils wherein the deicer is constructed in a conventional manner so that the inflatable tubes are also located on or immediately adjacent the stagnation line, the ice is not broken because the inflation tube pushes the ice cap forwardly before it breaks. The ice cap is then held onto the airfoil by the airstream. This in effect does not take advantage of the clamshell type of breaking which is so effective in a symmetrical as well as a non-symmetrical type of airfoil construction. The method of de-icing the airfoil can be improved by use of a deicer as described above, employing inflatable tubes on opposite side of the stagnation line by first inflating all of the tubes, the first set, on one side of the stagnation line and thence deflating such first set of tubes and simultaneously inflating all of the tubes, the second set, on the other side of the stagnation line, and thence repeating this cycle. The above construction of the deicer is particularly economical and effective in its deicing operation while requiring a minimum of power consumption.